Relays

The IB1004 + SB1004 combination has two low-power mechanical relays.

These relays can only handle relatively light loads — they are rated for 24V/1A. If your load is inductive in nature, then the power the relays can handle may actually be several times lower.

Relay Outputs

The relay outputs are on terminal block #4. Both normally closed and normally opened lines are provided for each relay.

Terminal #	Function
9	Relay 2, normally opened line
8	Relay 2, normally closed line
7	Relay 2, common line
6	Relay 1, normally opened line
5	Relay 1, normally closed line
4	Relay 1, common line
3	Serial port: RX (RS232); TX/RX+ (RS485)
2	Serial port: TX (RS232); TX/RX– (RS485)
1	System(common) ground

Relay Control

Two lines of the EM1000 (located on the NB10x0 network board) control the relays. On power-up, all EM1000 lines are configured as inputs and pulled up internally, keeping the relays off. To turn on a relay, set the corresponding control line LOW. Naturally, you need to configure these GPIO lines as outputs in order to be able to control the relays.

Line

Function

Corresponding EM1000 I/O line

IC1000 cable line

RELAY1 (output)

Relay 1 control:

HIGH (or input^*) — relay off
LOW — relay on

GPIO36

RELAY2 (output)

Relay 2 control:

HIGH (or input^*) — relay off
LOW — relay on

GPIO37

*GPIO line configured as input (default state)